Speaker: Jennifer Hollingsworth, Los Alamos

Speaker: Jennifer Hollingsworth, Functional Nanomaterials: Understanding & Controlling Light-Emission Properties From the Inside Out

Affiliation: Los Alamos

ABSTRACT:

Functional Nanomaterials: Understanding & Controlling Light-Emission Properties From the Inside Out
Solution-processed quantum dots (QDs) are finding applications in a wide-range of technologies from display and lighting to photovoltaics and photodetectors. We take advantage of an expanded “structural toolbox” to synthesize QDs with novel and optimized photophysical properties, especially stable and bright emission in the visible and infrared. We use advanced heterostructuring that employs bandgap engineering, thick (“giant”) or asymmetric shell growth, interfacial alloying, etc. In this way, we have synthesized QDs for which non-radiative processes, such as blinking, Auger recombination and photobleaching, have been reduced or even “turned off” at room temperature and exposed to air  (e.g., J. Am. Chem. Soc. 2012, 134, 9634; Nano Lett. 2012, 12, 5545; J. Am. Chem. Soc. 2017, 139, 11081; Nature Commun. 2017, 8, 15083; Adv. Funct. Mater. 2019, 29, 1809111). As part of this effort, we have developed new methods for evaluating processing-structure-function correlations toward materials-by-design. In this talk, I will discuss: (1) a “single-QD stress test” used to evaluate photodegradation processes (ACS Nano 2018, 12, 4206), and (2) an “inside-out” approach to establishing processing-structure-function correlations. By testing QDs at the level of single nanocrystals, we directly identify degradation mechanisms and associated reaction kinetics, which is not possible relying on device testing alone. We calculate activation energies for the photo-degradation processes specific to a QD composition or a QD synthesis procedure. Second, by performing multimodal characterization, we pinpoint the nanocrystal structural/chemical features responsible for desired vs. non-optimal properties, and their origin in processing. Taken together, the techniques enable a faster progression to ideal nanostructures that can then be integrated or assembled into functional devices and hybrid materials.

BIO:

Los Alamos National Laboratory (LANL) Fellow and American Physical Society Fellow, Division of Materials Physics, Dr. Hollingsworth is a Councilor for the American Chemical Society College & Surface Chemistry Division. She holds a BA in Chemistry from Grinnell College (Phi Beta Kappa) and a PhD degree in Inorganic Chemistry from Washington University in St. Louis. She joined LANL as a Director’s Postdoctoral Fellow in 1999, becoming a staff scientist in 2001. In 2013, she was awarded a LANL Fellows’ Prize for Research for her discovery and elaboration of non-blinking “giant” quantum dots (gQDs). In her role as staff scientist in the Center for Integrated Nanotechnologies (CINT; http://www.lanl.gov/expertise/profiles/view/jennifer-hollingsworth), a US DOE Nanoscale Science Research Center and User Facility, she endeavors to advance fundamental knowledge of optically active nanomaterials, targeting the elucidation of synthesis-nanostructure-properties correlations toward the rational design of novel functional materials. Her gQD design has been extended to multiple QD and other nanostructure systems, and several are being explored for applications from ultra-stable molecular probes for advanced single-particle tracking to solid-state lighting and single-photon generation. A recent focus of her group is to advance scanning probe nanolithography for precision placement of single nanocrystals into metasurfaces and plasmonic antennas.